Demonstration of the activity of P-glycoprotein by a semi-automated fluorometric method

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BACKGROUND: We have developed a semi-automated fluorometric method that utilizes ethidium bromide (EB), a common substrate of bacterial efflux pumps. The method is sufficiently sensitive to characterize the efflux pump systems of bacteria. Because EB is also recognized and extruded by ATP-binding cassette (ABC) transporters and these have similarity to P-glycoprotein (P-gp), the method has been extended for the evaluation of agents that can inhibit the extrusion of EB on a real-time basis by mouse lymphoma cells containing the human ABCB1 (mdr1) gene.

MATERIALS AND METHODS: Monitoring of uptake and extrusion of EB was assessed using the Rotor-Gene 3000 (Corbett Research) under different conditions.

RESULTS: Whereas extrusion of EB took place readily, the addition of known inhibitors of efflux pumps (verapamil, reserpine) caused retention of EB.

CONCLUSION: This method is inexpensive and allows the detection of neoplastic cells with increased efflux activity as well as the screening of large numbers of compounds for inhibition of the P-gp.

Original languageEnglish
Pages (from-to)2173-2177
Number of pages5
JournalAnticancer Research
Issue number6
Publication statusPublished - Jun 2009


  • Adrenergic Uptake Inhibitors
  • Animals
  • Automation
  • Biological Transport
  • Calcium Channel Blockers
  • Cell Survival
  • Drug Resistance, Multiple
  • Drug Resistance, Neoplasm
  • Ethidium
  • Fluorometry
  • Humans
  • Lymphoma, T-Cell
  • Mice
  • P-Glycoprotein
  • P-Glycoproteins
  • Reserpine
  • Verapamil
  • Journal Article
  • Research Support, Non-U.S. Gov't


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